Arrangement for driving vehicles by means of internal combustion machines



Sept. 8, 1936.

O. AKERMAN ARRANGEMENT FOR DRIVING VEHICLES BY MEANS OF INTERNAL COMBUSTION MACHINES Filed May 13, 1935 .Z/Yl flfOP.

O/of ike/71mm ,5 j ma Patented Sept. 8, 1935 UNITED STATES ARRANGEMENT FOR DRIVING VEHICLES BY MEANS OF INTERNAL COMBUSTION MACHINES Olof Akerman, Vasteras, Sweden, assignor to Allmanna Svenska Elektriska Aktiebolaget,

Vasteras, Sweden, a corporation of Sweden Application May 13,

1935, Serial No. 21,285

In Sweden May 12, 1934 2 Claims.

(Granted under the provisions of sec. 14, act of March 2, 1927; 357 0. G. 5)

In systems for driving railway cars, ships and other vehicles by means of Diesel engines or other internal combustion motors, in which the power is transmitted to the wheels of the cars by means 5 of an electrical transmission, several attempts have been made to effect such a regulation of the electrical transmission, that the load is automatically maintained at a constant value without any special attention from the operator.

The reason for these attempts is the desire to utilize the driving machinery as much as possible and to leave the operator free from a continuous observation of the load state of the driving machinery. Such observation is always necessary when the driving motors are of the internal combustion type and especially if they are Diesel motors, because an overloading of the motors is followed by poor combustion and overheating of the cylinders, pistons and valves, which means considerably increased maintenance costs.

In spite of the many attempts that have been made to solve this problem no solution satisfactory from all points of View has yet been found. It must be assumed that the reason for this is that all attempts have dealt only with the regulation of the electrical transmission, for instance by means of power relays, without taking into consideration the service properties of the Diesel motor.

Systems are, however, known in which the regulator of the Diesel motor has been combined with or acted upon the electrical transmission. These arrangements, however, have the disadvantage that the regulator for the electrical transmission must be arranged at or close to the Diesel motor. Further the movements of the regulator generally are too small to directly perform the actuation of the regulator for the electrical transmission. It is therefore necessary in this case to arrange special mechanical means for amplifying the movements of the Diesel motor regulator. Further in the above mentioned arrangements the regulation of the electrical transmission and of the Diesel motor are not independent of each other, which is necessary if a regulation according to the present invention shall be reached, that means a regulation which prevents any overloading of the Diesel motor but allows a full loading of it.

In order that the service conditions shall be as satisfactory as possible it is necessary that the driving machinery has the following properties: The operator of the vehicle must be in the position to freely utilize the available power according to the service conditions. He must further, if it is required by the service be able, by means of a single operation to adjust the electrical transmission to work with a maximum torque independently of the service conditions, i. e. train resistance and soon. The arrangement must further be such that the operator of the vehicle can overload the Diesel motor to a certain degree but only by a conscious operation. Such a conscious overloading, however, must be predetermined as to its magnitude either by the manufacturer of the motor or in the workshops of the railway company and must not be dependent upon the will of the operator. The regulation must further be such that a change in the service conditions of one or several cylinders of the motor, for instance by faults in the supply of the fuel, leakage between the cylinders and pistons and so on, is not followed by an overloading of the other cylinders. This means that for a given speed setting no more fuel may be supplied to each cylinder than corresponds to the speed setting in question.

It is further a great advantage if the working conditions of the motor and the electrical transmission can be observed from a central point by means of a single instrument. v

According to the present invention a regulation ideal from all points of view can be obtained. This is reached chiefly by regulating means for the fuel, which are soconstructed that only a certain predetermined maximum power can be taken out from the Diesel motor combined with an electrical transmission, which is provided withsuch regulating means that in spite of a limited power of the Diesel motor the operation of the system remains stable. The regulating means for the electrical transmission are further such that the load for a given setting of the speed controller remains practically constant.

In addition to the above mentioned advantages,

which are obtained by the invention, it makes possible the parallel service of a number of sets, the regulation of these sets being performed from a single point by means of a single controller.

The invention consists chiefly in that the Diesel motor is provided with a centrifugal regulator or some other regulator for the fuel injection. This regulator is provided with a device by means of which the fuel quantity injected in each cylinder is limited when the speed of the Diesel engine has decreased to a certain adjustable value. If a centrifugal regulator is employed, this limiting device merely consists of a simple stop. As the torque of the motor depends upon the quantity of the injected fuel, it will remain constant as long as the regulator restsagainst the above chine inserted in series in the field circuit of the railway car according to the invention, Fig. 2

mentioned stop. The above mentioned limitation of the fuel, however, must be combined with a certain flexibility in the electrical transmission. This flexibility must be such that the torque decreases rather rapidly when the speed of the motor decreases, and this is attained by the use of an electrical transmission generator which is a. self-exciting one, for instance a normal shunt generator, or by the use of a generator that has a separately fed field and is provided with suitable series windings. A better regulation is, however, generally reached by the use of separate regulating devices, for instance a regulating magenerator or by a regulator of the common type. In order to achieve the above mentioned flexibility this regulator or regulating machine must be provided with a device, which makes the regulating curve dependent upon the speed of the Diesel motor.

The above mentioned stop on the regulator of the Diesel motor may be yieldable to a certain degree and preferably so that the torque of the Diesel motor may be changed in a desired degree when the speed of the motor changes. So for instance the change of the movement may be such that the power delivered from the Diesel motor remains practically constant in spite of small fluctuations in the speed of such motor.

As the above mentioned stop of the Diesel motor regulator also may be adjustable, it is possible to overload the Diesel motor to a certain degree, but as above mentioned this degree should be predetermined.

On the accompanying drawing Fig. 1 shows a shows a centrifugal regulator for the Diesel motor, Fig. 3 a wiring diagram for the electrical transmission and Figs. 4 and 5 are diagrams showing the function of the system.

In Fig. 1, 27 is the railway car. I designates the Diesel motor, which is directly coupled to the generator 2 of the electrical transmission, and the exciter 1 is directly mounted on this generator. IT is a centrifugal regulator for the regulation of the fuel to the Diesel motor. 5 designates the electrical motors, which by means of the gears in known manner are coupled to the driving wheels 26 of the car. 16 are controllers arranged at each end of the car and may be alternatively connected in.

In Fig. 2, which shows the regulator for the Diesel motor, 22 is a rod, which moves up and down according to the speed of the motor. Connected to this rod is an arm 23, which is coupled to an arm 25 of the fuel valves 24. i8 is a stop, which limits the motion of the rod 22. Between this stop and the end of the rod 22 a roll 2| is arranged. This roll rests against the wedgeshaped rod I9, which may be moved in between the roll 2| and stop l8 for example by a solenoid 20. When this rod i9 is in the left position, the

roll 2! rests against the stop l8, and the rod 22 is then able to take a lower position than when the rod I9 is inserted between the roll 2| and stop l8. In the former case a large quantity of fuel is injected into the Diesel engine corresponding to a certain overload of it, whereas the position of the rod 22 when the rod l9 lies between 2| and I 8 corresponds to the normal maximum load of the engine. The stop 6 8 is shown as a fixed one but may of course also be made adjustable.

' In the Wiring diagram of Fig. 3, l designates the' Diesel engine. '2 is the generator and 3 a series winding of it. 4 is the separately fed field Winding, which is fed from the exciter l, which is directly coupled to the generator 2. In series with the field winding the regulator motor 8 is controller and is constructed as a regulable re-,

sistance' The motors 5 are of the series type .with field windings 6.

' motive force from the eXciter i, the resultant electromotive force driving the current through the field winding 4 will change in such a manner and thus'also the voltage of the generator 2 that the load remains practically constant independently of the current through the generator and motors. .This depends upon the fact that the voltage from the exciter I and the counteracting voltage from the motor 8 varies approximately along an hyperbola and thus also the voltage of the generator 2. The product of the voltage of the generator 2 and the current through it will therefore remain practically constant. Only when the speed of the Diesel motor changes, the torque and thus the load of the electrical transmission will change rather rapidly with decreasing speed of the Diesel motor. This depends upon the fact that with decreasing speed of the Diesel motor the voltage of the exciter l dereases. As the voltage of the exciter' is balanced by the voltage from the battery l5, which has a practically constant voltage, a very small decrease in the voltage of the exciter 1 causes a rather considerable change in the current through the Winding 9 and thus a rather considerable change 'in the counteracting voltage of the motor 8, i. e. this voltage rises because the winding 9 is counteracting the winding ii]. A rise in the voltage of the motor 8 is, however, equivalent to a decrease of the torque of the generator 2.

The function of the arrangement is illustrated by the diagrams Figs. 4 and 5. In Fig. 4 the line A-B is the torque of the Diesel engine as a function of its speed during the period when it does not have its full load. The line BE is the torque of it when the regulator has reached the above mentioned stop. The lines I and 2 are the torque of the electrical transmission in the case that the torque is regulated to a constant value, and the line i represents a larger torque than the line '2. The noload speed of the Diesel engine is designated by no and the normal speed by 1111. As seen from the diagram the speed of the Diesel motor will decrease from no to m when the torque increases. As soon as the torque has reached the value Man a further increase of the torque is not possible due to the stop according to the invention, because when the speed of the Diesel motor has decreased to the value 7111 the regulator has reached this stop.

If the torque of the electrical transmission rises from Zero to the value 2, the torque of the Diesel motor decreases from no to m. If on the other hand the torque of the electrical transmis From this diagram it is therefore clear that the combination of the regulation of the electrical transmission on constant torque with a limitation of the injected quantity of fuel will lead to instability, because if the torque of the electrical transmission is adjusted to a value near to the value corresponding to the maximum injected quantity of fuel, each irregularity in the regulation or in the service of the machine will be accompanied by a stoppage of the Diesel motor. In order to understand this it is only necessary to imagine that the torque of the electrical transmission has the value 2 and that ignition fails in one cylinder of the Diesel motor. In this case the torque of the Diesel motor would immediately decrease to a value lower than the value 2 and therefore the Diesel motor would stop.

In order to reach stability it is therefore necessary that the electrical transmission has a torque characteristic, which falls with decreasing speed of the Diesel motor, because in this case there will always be an intersection point between the torque line of the electrical transmission and the torque line AB--E of the Diesel motor. In order that this intersection point will be reached without any considerable decrease of the speed of the Diesel engine the torque of the electrical transmission must decrease rather rapidly with decreasing speed of the motor. This is shown in Fig. 5, where the lines 3 and 4 are such torque curves. A change in the properties of the electrical transmission, for instance by changes in the temperature and so on, only means a small parallel removal of the above mentioned lines 3 or 4, but as seen from the diagram a removal of these lines will not be accompanied by any change in the transmitted torque and the change in the speed will also be very unimportant.

Even in the case that the service conditions of the Diesel motor change, for instance if ignition fails in a cylinder or if the supply of the fuel is changed, the change in the speed will be very small. This is explained in Fig. 5 by the dotted line, which line designates the torque of the Diesel motor after such a disturbance. In this case the speed will decrease from the value 113 to 113 In the preceding it is assumed that the Diesel motor works with an injected quantity of fuel per cycle and cylinder corresponding to the full load of the Diesel engine. In the case, however, when the Diesel engine is not running with full load, the delivery of power may be adjusted in a plurality of ways, for instance thereby that with maintained position of the stop the speed of the Diesel motor is changed by changing the tension of the regulator spring. With constant speed the power also may be changed by an adjustment of the stop of the regulator and further with practically constant speed and unchanged position of the stop the power can be set to any value up to the maximum value by changing the resistance in the field circuit of the generator, and in the case that a regulating machine is provided, the power can be changed by changing the current through the separately fed winding of this machine, for instance by changing the current in the winding 9 of the regulator motor 8 in some known manner.

When the Diesel motor is not running with full load, it is not necessary that the electrical transmission has a falling torque characteristic, 1. e.

when the Diesel motor works between the speed limits no and 1111. In this case the inclination of the torque curves 5 and 6 is arbitrary. Only when the maximum torque value B is reached, it is necessary that the torque characteristic is a falling one.

In the above described arrangement the electrical transmission has obtained its flexibility by means of the regulator motor combined with the directly driven exciter and accumulator battery 15, but this flexibility may as already mentioned be reached by some selfregulating machine or by a separate regulator. In the latter caseit is, however, necessary that this regulator, at least after the value B has been reached, is dependent of the speed of the Diesel motor. So may for instance, a common regulator be used, which is provided with a coil, which in some way or other puts the regulator in dependence of the speed of the Diesel motor. This coil may be connected in firstly when the Diesel motor regulator reaches the stop and then by means of contacts arranged on the regulator or on this stop.

In the point B the load conditions are discontinuously changed, so that the torque at once takes a constant value. That this point is reached may easily be seen on a measuring instrument, and by means of this instrument it is therefore possible tocontrol if the Diesel motor works with its full torque or if the motor has lost its power.

I claim as my invention:

1. A driving system for railway cars and other vehicles comprising at least one internal combustion motor, a regulating device for regulation of the supply of the fuel for said motor, a stopping device on said regulating device for limitation of the fuel quantity injected into said motor, a generator having a field circuit and coupled to said motor, driving means for the vehicle, at least one electrical motor geared to the driving means of the vehicle, a main circuit formed by the electrical connections between said generator and said electrical motor, an exciter for said generator coupled to said internal combustion motor, a regulating device inserted in the field circuit of the generator, at least two windings on said regulating device, one of which is connected to the said exciter in series with a counteracting source of voltage, and the other is inserted in the main circuit of the generator.

2. A driving system for railway cars, and other vehicles, comprising at least one internal combustion motor, a centrifugal regulator for regulation of the supply of the fuel to said motor, a stopping device on said regulator for limitation of the fuel quantity injected into said motor, a generator having a field circuit and coupled to said motor, driving means for the vehicle, electrical motors geared to the driving means of the vehicle, a main circuit formed by electrical connections between said generator and said motor, an exciter for said generator coupled to said internal combustion motor, a regulating machine inserted in series in the said field circuit of the generator said machine being provided with two field windings of which one is inserted in the main circuit and the other is fed from the exciter in series with a counteracting source of voltage.

OLOF AKERMAN. 

